1. Technical Field
The present exemplary embodiment relates to air springs with elastomeric bodies having integrated sensor systems. It finds particular application in conjunction with monitoring physical and engineering properties of the air spring with embedded micro/nano-sized sensors, and will be described with particular reference to vehicle air springs. However, it is to be appreciated that the subject matter of the present disclosure is also amenable to other applications and environments, and that the specific uses shown and described herein are merely exemplary. For example, the subject matter of the present disclosure could be used in air springs for transportation vehicles, height adjusting systems and actuators associated with industrial machinery, and/or other such equipment.
2. Background Information
It is well known that land vehicles of most types and kinds are outfitted with a suspension system that supports a sprung mass (e.g., a body or chassis) of the vehicle on an unsprung mass (e.g., axles or wheel-engaging members) of the vehicle. It is also well known for some suspension systems to include air spring devices that are operatively connected between the sprung and unsprung masses of the vehicle. Typically, such air spring devices include two relatively rigid end members that are sealingly connected to respective open ends of a flexible spring wall to at least partially form a spring chamber therebetween.
The spring wall of a conventional gas load bearing device is adapted to flex during dynamic operation and use of the air spring device and is therefore normally made from a flexible, elastomeric material. During operation, the air spring device is loaded such that opposing forces act against the end members. It is well recognized in the art that the flexible spring wall does not itself support the load. Rather, the pressurized gas retained within the gas spring device by the spring wall acts against the end members and thereby provides forces capable of supporting loads applied to the end members.
The result of the work performed by the viscoelastic materials can be indicated by temperature, a thermodynamic quantity, as a measure of the useful work lost to heat. Air springs are designed to withstand repeated internal and external forces and the resulting temperatures within an operational window at various loads and internal pressures. When an elastomeric article experiences conditions beyond this operational window, the performance of the article can be shortened. For example, in some situations, a vehicle air spring that is being improperly used may include components that are subjected to excessive shear forces during use (e.g.: repeated cyclic deformation). These internal forces generate heat that will raise the internal temperature of the air spring. Overheated air springs may eventually break down and impair the air spring performance.
Today's vehicles also include actively-managed suspension and braking systems. These systems infer or assume data about the relationship between the air spring and the road surface. Vehicle manufacturers desire a system to obtain measurable real-time engineering data from the air spring so that these data may be used to actively manage the vehicle's operation.
It is therefore desirable to sense parameters experienced by the air springs such as forces including stresses and strains, temperatures, vibrations, and other conditions to provide useful information concerning the status of the air spring and its components.